Wear and oxidation characteristics of aluminized INC738 with different pack contents

Abstract

One important factor in determining how long Ni-based superalloys will last is their resistance to oxidation. Another important issue is the wear resistance under harsh service conditions. In this study, unlike many other Ni-based superalloys, the INC738 alloy was used and subjected to an aluminizing process at 800 degrees C for 4 h. In addition, Si and Co-Si additions were applied simultaneously, and mechanical properties and oxidation resistance were tested. While the Ni2Al3 phase was dominant in the coatings, the coating thickness decreased with the addition of Co, and at the same time, microhardness increased from 400 HV to 1200 HV. The coating thickness was measured as the thinnest at 40 mu m, while the unalloyed Al coating reached up to 110 mu m. In nanoindentation tests, it was determined that the nanoindentation Young's modulus (EIT) changed from 237 GPa to 232-277 GPa, and the hardness increased more than 3 times from 6.74 GPa to 14.24-20.63 GPa. With aluminizing, the surface of INC738 is made more wear resistant. As a result of cyclic high-temperature oxidation tests, significant improvement was achieved in the oxidation resistance of the aluminized INC738 sample. Lower mass gain was obtained due to the dominant alumina structure formed on the surface.